Patent GB-1313403-A (GB)
Title: Rotary liquid strainer and method of making the same
IPC: B01D33/00
Filed: 1970-04-29
Abstract: 1313403 Rotary drum filters G R EVANS 29 April 1970 20681/70 Heading B1D The tank enclosing a rotary, outward flow filter drum 19 is moulded on site out of concrete and comprises an integral dividing wall 16, having a central opening 21 in which is an integral pedestal 23, and end wall 13 having a recess 29 whose lower end (Fig. 2, not shown) is widened, said pedestal and lower end supporting the ends of a fixed hollow axle 22 on which the drum is mounted. Wall 16 separates an inlet chamber 17, to which water to be filtered is delivered, from chamber 18 in which the drum 19 is located. Integral weirs 30, 31 partition chamber 18 and filtered water flows over them for discharge at various points 34. The drum is rotated by a toothed belt drive 42 from a motor (40) in an overhead bridge (Fig. 5, not shown), which is supported on a roof (15) which includes removable access slabs. The bridge also encloses nozzles which direct filtrate or steam on to the upper part of the drum, washing solids into hoppers 47, mounted on axle 22, through whose open end(s) such solids are removed. Channel 35 receives liquid from inlet chamber 17 if the drum clogs or the level rises for other reasons, and may discharge such liquid into chamber 18 downstream of the drum, which is thus by-passed. Drum 19 has a surface of stainless steel mesh of 20-60 micron aperture. In constructing, the tank and various walls therein and pedestal 23 are cast in reinforced concrete, pedestal 23 receiving a pair of threaded collars 56 (Fig. 9) which are welded to the reinforcing bars (Fig. 7, not shown). A saddle 24 is supported on the pedestal by adjustable jack screws .61 engaging in collars 56, and the recess 29 in end wall 13 is similarly fitted. The saddles are adjusted level and epoxy resin 68 filled into the gaps between saddles and concrete. The preformed drum 19 mounted rotatably on shaft 22 (Fig. 14, not shown) is lowered into the chamber 18 and the shaft ends secured to saddles 24 by straps 25: The saddles are readjusted and any new gaps filled, and set screws 66, 67 secure the shaft to straps and saddles. Alternatively, saddles 24 may be rigidly secured to pedestal and recess in the first instance, and any lack of alignment is then corrected by machining the saddles in situ.  Fig. 11 illustrates a sliding seal formed between an annular flange 70 on the end of the drum and a part-annular flange 71 which is adjustably secured to wall 16 around opening 21. A PVC sleeve 73 is secured to the inside of one flange and slidably engages the other. An outer strap 74 is then fitted, which embraces the flanges below the water line but has its two ends secured to the bridge (Fig. 5) by spring loading means. In Fig. 1 drum 19 is open at one end only, adjacent opening 21, and ghost lines indicate how a similar unit may be arranged back-toback with that shown. Fig. 15 (not shown) illustrates how drums open at two ends may be arranged in rows in a common tank divided by various walls which form inlet channels (97, 97') and outlet chambers 33 between drums discharging into duct (99). In Fig. 16 inlet channel 113. opens into individual inlet chambers via closable valves 131. Filtrate outlet channels 123, 126 are arranged at a higher level, and weirs 116 separate the inlet chambers and outlet channels and serve as by-pass overflows. These parts of weirs 161 are higher than those separating the outlet channels 123 from the chambers enclosing the drums.